Wls expression is localized to the cerebellar RL during embryonic development. Expression of Wls transcript and protein in the cerebellum, across embryonic development, is revealed by in situ hybridization (A–C) and immunohistochemistry (D–F) analyses on wild-type brain tissues collected at E13.5, E15.5, and E18.5. Wls expression is localized predominately to the cerebellar RL at all ages examined (arrows). Wls is also expressed at the ISO region (asterisks in A and D), in the cells of the choroid plexus of the fourth ventricle, and in the meninges over the cerebellum and roof plate. CP, choroid plexus; EGL, external germinal layer; VZ, ventricular zone. Scale bars: 100 μm.